Doug was the first round draft pick of the San Diego Padres in 1986, but did not make his major league debut until 1992 because of injuries sustained in the minors. Initially a starter, Brocail went 4–13 in his first full season (1993) before being converted to relief. More arm problems kept Brocail out of the major leagues for nearly four years (2000–04).

In November 2015, Brocail was offered a spot as the Texas Rangers pitching coach by Rangers manager Jeff Banister. Brocail accepted the position, replacing the departed Mike Maddux. Brocail leads a highly regarded pitching staff that is led by ace Cole Hamels in 2017.[3]

Doug and his wife Lisa have five daughters: Taylor, McKinzie, Madisyne, Camdyn and Parker Elisabeth. The family lives in Missouri City, Texas.

On September 13, 2004, Brocail was involved in an incident at the McAfee Coliseum, when the Texas Rangers were playing the Oakland Athletics. His rookie teammate Frank Francisco, angry at a fan for heckling Brocail, hoisted a folded chair into the stands, striking a female fan and breaking her nose.[4] Brocail would later pitch ​1⁄3 of an inning.

Brocail underwent angioplasty on March 11, 2006. He had complained of chest tightness that radiated into both arms. He already was being treated for an abscessed tooth and asthma. He only returned to the active roster on July 14.